RRM reporting method in wireless communication system, and apparatus supporting same

ABSTRACT

The present invention discloses a method for a terminal reporting radio resource management (RRM) to a base station, and an apparatus supporting the same. More specifically, the present invention discloses a method for a terminal, if a base station transmits signals including an RRM reference signal (RS) by using one or more analogue beams for each symbol, performing RRM measurement in correspondence with the same, and reporting the measured RRM information; and an apparatus supporting the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/065,740, filed on Jun. 22, 2018, now allowed, which is a NationalStage application under 35 U.S.C. § 371 of International Application No.PCT/KR2017/005673, filed on May 31, 2017, which claims the benefit ofU.S. Provisional Application No. 62/377,523, filed on Aug. 19, 2016,U.S. Provisional Application No. 62/345,006, filed on Jun. 3, 2016, andU.S. Provisional Application No. 62/343,176, filed on May 31, 2016. Thedisclosures of the prior applications are incorporated by reference intheir entirety.

TECHNICAL FIELD

The following description relates to a wireless communication system,and more particularly, to a method for reporting, by a terminal, radioresource management (RRM) to a base station in a wireless communicationsystem and apparatuses supporting the same.

More specifically, the following description relates to a method forperforming RRM measurement and reporting the measured RRM information bya terminal when a base station transmits a signal including an RRMreference signal (RS) by applying one or more analog beams on asymbol-by-symbol basis, and apparatuses supporting the same.

BACKGROUND

Wireless access systems have been widely deployed to provide varioustypes of communication services such as voice or data. In general, awireless access system is a multiple access system that supportscommunication of multiple users by sharing available system resources (abandwidth, transmission power, etc.) among them. For example, multipleaccess systems include a Code Division Multiple Access (CDMA) system, aFrequency Division Multiple Access (FDMA) system, a Time DivisionMultiple Access (TDMA) system, an Orthogonal Frequency Division MultipleAccess (OFDMA) system, and a Single Carrier Frequency Division MultipleAccess (SC-FDMA) system.

SUMMARY

An object of the present invention devised to solve the problem lies ina method and apparatus for reporting RRM to a base station.

In particular, it is an object of the present invention to provide amethod for performing, by a terminal, RRM measurement usable for thesignal transmission/reception operation and reporting the measured RRMto a base station in a case where signals are transmitted and receivedbetween the base station and the terminal (or user equipment) accordingto an analog beamforming technique, and an apparatus therefor.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

The present invention provides a method and apparatus for reportingradio resource management (RRM) by a terminal in a wirelesscommunication system.

In one aspect of the present invention, provided herein is a method forperforming Radio Resource Management (RRM) reporting by a terminal in awireless communication system, the method including receiving a signaltransmitted by applying one or more analog beams thereto on asymbol-by-symbol basis, the signal including an RRM reference signal(RS), performing RRM measurement including at least one of receivedpower measurement of the RRM RS and received power measurement of asignal received in a specific symbol, based on the received signal, andreporting measured RRM information to a base station.

In another aspect of the present invention, provided herein is aterminal for performing Radio Resource Management (RRM) reporting to abase station in a wireless communication system, the terminal (or userequipment) including a transmitter, a receiver, and a processorconnected to the transmitter and the receiver, wherein the processor isconfigured to receive a signal transmitted by applying one or moreanalog beams thereto on a symbol-by-symbol basis, the signal includingan RRM reference signal (RS), perform RRM measurement including at leastone of received power measurement of the RRM RS and received powermeasurement of a signal received in a specific symbol, based on thereceived signal, and report measured RRM information to the basestation.

The RRM RS may include one or more of a synchronization signal (SS) or ademodulation reference signal in a physical broadcast channel.

For example, the RRM RS may be transmitted in a frequency resourceregion of a predetermined size in a subframe in which a synchronizationsignal (SS) is transmitted, wherein a numerology identical to anumerology applied to the SS may be applied to the RRM RS.

In another example, the RRM RS may be transmitted in a frequencyresource region of a predetermined size within a subframe after apredetermined number of subframes from a subframe in which asynchronization signal (SS) is transmitted.

In another example, the RRM RS may be transmitted in a frequencyresource region of a predetermined size in a predetermined subframe,wherein a numerology configured by default may be applied to the RRM RS.

The RRM reporting method may further include receiving measurementconfiguration information from the base station. Herein, the RRM RS maybe transmitted in a frequency resource region of a predetermined sizeindicated by the measurement configuration information in a subframeindicated by the measurement configuration information, wherein anumerology indicated by the measurement configuration information may beapplied to the RRM RS.

In addition, the RRM RS may be generated by inserting, according to anumerology applied by the base station transmitting the RRM RS, one ormore samples of zero between respective samples of an RRM RS sequencegenerated based on a numerology configured by default, wherein theterminal may receive the RRM RS based on the numerology configured bydefault.

Herein, the RRM RS may be transmitted through one or more antenna ports,wherein an independent analog beam may be applied to each of the one ormore antenna ports.

In this case, a different frequency resource and sequence may beallocated to an RRM RS for each of the one or more antenna ports.

Alternatively, the terminal may measure received power of the RRM RS foreach of the antenna ports to perform the received power measurement ofthe RRM RS.

In addition, when the RRM RS includes a plurality of types, the terminalmay independently measure received power of each type of the RRM RS asthe received power measurement of the RRM RS, or the terminal maymeasure RRM received power of a single value by applying a weight havinga predetermined magnitude to the received power of each type of the RRMRS as the received power measurement of the RRM RS.

In addition, the terminal may measure received power for a signalreceived within the specific symbol for each of the one or more analogbeams in the received power measurement of the signal received in thespecific symbol.

The RRM reporting method may further include receiving, from the basestation, instruction information instructing reporting of an aperiodicRRM measurement result. Herein, the terminal may report the measured RRMinformation to the base station through a physical layer signal or aMedium Access Control (MAC) layer signal after a predetermined time froma moment at which the instruction information is received.

In addition, when the RRM RS is transmitted through one or more antennaports, the measured RRM information may include one of RRM measurementresult information averaged over the one or more antenna ports, RRMmeasurement result information per antenna port for a certain number ofanalog beams of the one or more analog beams, and RRM measurement resultinformation averaged over antenna ports for a certain number of analogbeams of the one or more analog beams.

In addition, when the RRM RS is transmitted through one or more antennaports, the terminal may perform the RRM measurement on one or moreantenna ports satisfying a specific condition, wherein the measured RRMinformation may include identification information about the one or moreantenna ports satisfying the specific condition.

The RRM reporting method may further include reporting, by the terminal,a maximum number of measurable RRM measurement targets to the basestation, and receiving measurement configuration information from thebase station. Herein, the RRM RS may be transmitted in a frequencyresource region of a predetermined size indicated by the measurementconfiguration information in a subframe indicated by the measurementconfiguration information, wherein the terminal may perform the RRMmeasurement only on RRM measurement targets corresponding to the maximumnumber of measurable RRM measurement targets among RRM measurementtargets indicated by an RRM measurement target list included in themeasurement configuration information.

In addition, the signal transmitted by the base station may betransmitted by applying one or more independent analog beams for eachsymbol.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

As is apparent from the above description, the embodiments of thepresent disclosure have the following effects.

According to the present invention, a base station may transmit a signalto a terminal by applying the analog beamforming technique. Inparticular, the base station may transmit a signal by applying one ormore analog beams on a symbol-by-symbol basis.

In this case, according to the present invention, the terminal mayefficiently measure the RRM for the signal transmitted using the analogbeamforming technique and provide the information to the base station.

Thereby, the base station according to the present invention mayimplement an efficient analog beamforming method based on theinformation.

The effects that can be achieved through the embodiments of the presentinvention are not limited to what has been particularly describedhereinabove and other effects which are not described herein can bederived by those skilled in the art from the following detaileddescription. That is, it should be noted that the effects which are notintended by the present invention can be derived by those skilled in theart from the embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, provide embodiments of the presentinvention together with detail explanation. Yet, a technicalcharacteristic of the present invention is not limited to a specificdrawing. Characteristics disclosed in each of the drawings are combinedwith each other to configure a new embodiment. Reference numerals ineach drawing correspond to structural elements.

FIG. 1 is a diagram illustrating physical channels and a signaltransmission method using the physical channels;

FIGS. 2A and 2B are diagrams illustrating exemplary radio framestructures;

FIG. 3 is a diagram illustrating an exemplary resource grid for theduration of a downlink slot;

FIG. 4 is a diagram illustrating an exemplary structure of an uplinksubframe;

FIG. 5 is a diagram illustrating an exemplary structure of a downlinksubframe;

FIG. 6 is a diagram illustrating a self-contained subframe structureapplicable to the present invention;

FIGS. 7 and 8 are diagrams illustrating representative methods forconnecting TXRUs to antenna elements;

FIG. 9 is a diagram schematically illustrating a hybrid beamformingstructure from the perspective of a TXRU and physical antennas;

FIG. 10 is a diagram schematically illustrating a beam sweepingoperation for a synchronization signal and system information in adownlink transmission procedure;

FIG. 11 is a diagram illustrating RRM RSs that can be defined fornumerologies having subcarrier spacings which are 1 times, ½ times, ⅓times, and ¼ times the subcarrier spacing of the default numerology;

FIG. 12 is a diagram illustrating a case where the subcarrier spacing ofthe default numerology is 30 kHz and the subcarrier spacing ofNumerology X is 15 kHz;

FIG. 13 is a diagram schematically illustrating a BRS for each antennaport from the perspective of a UE or a base station;

FIG. 14 is a diagram schematically illustrating a configuration fortransmitting an additional RS for BRS antenna port 0 in the example ofFIG. 13 in resources corresponding to other antenna ports through thesame analog beam; and

FIG. 15 is a diagram illustrating a configuration of a terminal and abase station in which the proposed embodiments may be implemented.

DETAILED DESCRIPTION

The embodiments of the present disclosure described below arecombinations of elements and features of the present disclosure inspecific forms. The elements or features may be considered selectiveunless otherwise mentioned. Each element or feature may be practicedwithout being combined with other elements or features. Further, anembodiment of the present disclosure may be constructed by combiningparts of the elements and/or features. Operation orders described inembodiments of the present disclosure may be rearranged. Someconstructions or elements of any one embodiment may be included inanother embodiment and may be replaced with corresponding constructionsor features of another embodiment.

In the description of the attached drawings, a detailed description ofknown procedures or steps of the present disclosure will be avoided lestit should obscure the subject matter of the present disclosure. Inaddition, procedures or steps that could be understood to those skilledin the art will not be described either.

Throughout the specification, when a certain portion “includes” or“comprises” a certain component, this indicates that other componentsare not excluded and may be further included unless otherwise noted. Theterms “unit”, “-or/er” and “module” described in the specificationindicate a unit for processing at least one function or operation, whichmay be implemented by hardware, software or a combination thereof. Inaddition, the terms “a or an”, “one”, “the” etc. may include a singularrepresentation and a plural representation in the context of the presentdisclosure (more particularly, in the context of the following claims)unless indicated otherwise in the specification or unless contextclearly indicates otherwise.

In the embodiments of the present disclosure, a description is mainlymade of a data transmission and reception relationship between a BaseStation (BS) and a User Equipment (UE). A BS refers to a terminal nodeof a network, which directly communicates with a UE. A specificoperation described as being performed by the BS may be performed by anupper node of the BS.

Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with a UE may be performed by the BS, or network nodesother than the BS. The term ‘BS’ may be replaced with a fixed station, aNode B, an evolved Node B (eNode B or eNB), an Advanced Base Station(ABS), an access point, etc.

In the embodiments of the present disclosure, the term terminal may bereplaced with a UE, a Mobile Station (MS), a Subscriber Station (SS), aMobile Subscriber Station (MSS), a mobile terminal, an Advanced MobileStation (AMS), etc.

A transmission end is a fixed and/or mobile node that provides a dataservice or a voice service and a reception end is a fixed and/or mobilenode that receives a data service or a voice service. Therefore, a UEmay serve as a transmission end and a BS may serve as a reception end,on an UpLink (UL). Likewise, the UE may serve as a reception end and theBS may serve as a transmission end, on a DownLink (DL).

The embodiments of the present disclosure may be supported by standardspecifications disclosed for at least one of wireless access systemsincluding an Institute of Electrical and Electronics Engineers (IEEE)802.xx system, a 3rd Generation Partnership Project (3GPP) system, a3GPP Long Term Evolution (LTE) system, and a 3GPP2 system. Inparticular, the embodiments of the present disclosure may be supportedby the standard specifications, 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS36.213, 3GPP TS 36.321 and 3GPP TS 36.331. That is, the steps or parts,which are not described to clearly reveal the technical idea of thepresent disclosure, in the embodiments of the present disclosure may beexplained by the above standard specifications. All terms used in theembodiments of the present disclosure may be explained by the standardspecifications.

Reference will now be made in detail to the embodiments of the presentdisclosure with reference to the accompanying drawings. The detaileddescription, which will be given below with reference to theaccompanying drawings, is intended to explain exemplary embodiments ofthe present disclosure, rather than to show the only embodiments thatcan be implemented according to the disclosure.

The following detailed description includes specific terms in order toprovide a thorough understanding of the present disclosure. However, itwill be apparent to those skilled in the art that the specific terms maybe replaced with other terms without departing the technical spirit andscope of the present disclosure.

For example, the term, TxOP may be used interchangeably withtransmission period or Reserved Resource Period (RRP) in the same sense.Further, a Listen-Before-Talk (LBT) procedure may be performed for thesame purpose as a carrier sensing procedure for determining whether achannel state is idle or busy, CCA (Clear Channel Assessment), CAP(Channel Access Procedure).

Hereinafter, 3GPP LTE/LTE-A systems are explained, which are examples ofwireless access systems.

The embodiments of the present disclosure can be applied to variouswireless access systems such as Code Division Multiple Access (CDMA),Frequency Division Multiple Access (FDMA), Time Division Multiple Access(TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), SingleCarrier Frequency Division Multiple Access (SC-FDMA), etc.

CDMA may be implemented as a radio technology such as UniversalTerrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented asa radio technology such as Global System for Mobile communications(GSM)/General packet Radio Service (GPRS)/Enhanced Data Rates for GSMEvolution (EDGE). OFDMA may be implemented as a radio technology such asIEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Evolved UTRA(E-UTRA), etc.

UTRA is a part of Universal Mobile Telecommunications System (UMTS).3GPP LTE is a part of Evolved UMTS (E-UMTS) using E-UTRA, adopting OFDMAfor DL and SC-FDMA for UL. LTE-Advanced (LTE-A) is an evolution of 3GPPLTE. While the embodiments of the present disclosure are described inthe context of a 3GPP LTE/LTE-A system in order to clarify the technicalfeatures of the present disclosure, the present disclosure is alsoapplicable to an IEEE 802.16e/m system, etc.

1. 3GPP LTE/LTE-A System

In a wireless access system, a UE receives information from an eNB on aDL and transmits information to the eNB on a UL. The informationtransmitted and received between the UE and the eNB includes generaldata information and various types of control information. There aremany physical channels according to the types/usages of informationtransmitted and received between the eNB and the UE.

FIG. 1 illustrates physical channels and a general signal transmissionmethod using the physical channels, which may be used in embodiments ofthe present disclosure.

When a UE is powered on or enters a new cell, the UE performs initialcell search (S11). The initial cell search involves acquisition ofsynchronization to an eNB. Specifically, the UE synchronizes its timingto the eNB and acquires information such as a cell Identifier (ID) byreceiving a Primary Synchronization Channel (P-SCH) and a SecondarySynchronization Channel (S-SCH) from the eNB.

Then the UE may acquire information broadcast in the cell by receiving aPhysical Broadcast Channel (PBCH) from the eNB.

During the initial cell search, the UE may monitor a DL channel state byreceiving a Downlink Reference Signal (DL RS).

After the initial cell search, the UE may acquire more detailed systeminformation by receiving a Physical Downlink Control Channel (PDCCH) andreceiving a Physical Downlink Shared Channel (PDSCH) based oninformation of the PDCCH (S12).

To complete connection to the eNB, the UE may perform a random accessprocedure with the eNB (S13 to S16). In the random access procedure, theUE may transmit a preamble on a Physical Random Access Channel (PRACH)(S13) and may receive a PDCCH and a PDSCH associated with the PDCCH(S14). In the case of contention-based random access, the UE mayadditionally perform a contention resolution procedure includingtransmission of an additional PRACH (S15) and reception of a PDCCHsignal and a PDSCH signal corresponding to the PDCCH signal (S16).

After the above procedure, the UE may receive a PDCCH and/or a PDSCHfrom the eNB (S17) and transmit a Physical Uplink Shared Channel (PUSCH)and/or a Physical Uplink Control Channel (PUCCH) to the eNB (S18), in ageneral UL/DL signal transmission procedure.

Control information that the UE transmits to the eNB is genericallycalled Uplink Control Information (UCI). The UCI includes a HybridAutomatic Repeat and reQuest Acknowledgement/Negative Acknowledgement(HARQ-ACK/NACK), a Scheduling Request (SR), a Channel Quality Indicator(CQI), a Precoding Matrix Index (PMI), a Rank Indicator (RI), etc.

In the LTE system, UCI is generally transmitted on a PUCCH periodically.However, if control information and traffic data should be transmittedsimultaneously, the control information and traffic data may betransmitted on a PUSCH. In addition, the UCI may be transmittedaperiodically on the PUSCH, upon receipt of a request/command from anetwork.

FIGS. 2A and 2B illustrate exemplary radio frame structures used inembodiments of the present disclosure.

FIG. 2A illustrates frame structure type 1. Frame structure type 1 isapplicable to both a full Frequency Division Duplex (FDD) system and ahalf FDD system.

One radio frame is 10 ms (Tf=307200·Ts) long, including equal-sized 20slots indexed from 0 to 19. Each slot is 0.5 ms (Tslot=15360·Ts) long.One subframe includes two successive slots. An ith subframe includes2ith and (2i+1)th slots. That is, a radio frame includes 10 subframes. Atime required for transmitting one subframe is defined as a TransmissionTime Interval (TTI). Ts is a sampling time given as Ts=1/(15kHz×2048)=3.2552×10−8 (about 33 ns). One slot includes a plurality ofOrthogonal Frequency Division Multiplexing (OFDM) symbols or SC-FDMAsymbols in the time domain by a plurality of Resource Blocks (RBs) inthe frequency domain.

A slot includes a plurality of OFDM symbols in the time domain. SinceOFDMA is adopted for DL in the 3GPP LTE system, one OFDM symbolrepresents one symbol period. An OFDM symbol may be called an SC-FDMAsymbol or symbol period. An RB is a resource allocation unit including aplurality of contiguous subcarriers in one slot.

In a full FDD system, each of 10 subframes may be used simultaneouslyfor DL transmission and UL transmission during a 10-ms duration. The DLtransmission and the UL transmission are distinguished by frequency. Onthe other hand, a UE cannot perform transmission and receptionsimultaneously in a half FDD system.

The above radio frame structure is purely exemplary. Thus, the number ofsubframes in a radio frame, the number of slots in a subframe, and thenumber of OFDM symbols in a slot may be changed.

FIG. 2B illustrates frame structure type 2. Frame structure type 2 isapplied to a Time Division Duplex (TDD) system. One radio frame is 10 ms(Tf=307200·Ts) long, including two half-frames each having a length of 5ms (=153600·Ts) long. Each half-frame includes five subframes each being1 ms (=30720·Ts) long. An ith subframe includes 2ith and (2i+1)th slotseach having a length of 0.5 ms (Tslot=15360·Ts). Ts is a sampling timegiven as Ts=1/(15 kHz×2048)=3.2552×10−8 (about 33 ns).

A type-2 frame includes a special subframe having three fields, DownlinkPilot Time Slot (DwPTS), Guard Period (GP), and Uplink Pilot Time Slot(UpPTS). The DwPTS is used for initial cell search, synchronization, orchannel estimation at a UE, and the UpPTS is used for channel estimationand UL transmission synchronization with a UE at an eNB. The GP is usedto cancel UL interference between a UL and a DL, caused by themulti-path delay of a DL signal.

[Table 1] below lists special subframe configurations (DwPTS/GP/UpPTSlengths).

TABLE 1 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Special Normal Extended Normal Extended subframecyclic prefix cyclic prefix cyclic prefix cyclic prefix configurationDwPTS in uplink in uplink DwPTS in uplink in uplink 0  6592 · T_(s) 2192· T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 1 19760 ·T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600· T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 · T_(s) 5  6592· T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 · T_(s) 23040 ·T_(s) 7 21952 · T_(s) — — — 8 24144 · T_(s) — — —

FIG. 3 illustrates an exemplary structure of a DL resource grid for theduration of one DL slot, which may be used in embodiments of the presentdisclosure.

Referring to FIG. 3, a DL slot includes a plurality of OFDM symbols inthe time domain. One DL slot includes 7 OFDM symbols in the time domainand an RB includes 12 subcarriers in the frequency domain, to which thepresent disclosure is not limited.

Each element of the resource grid is referred to as a Resource Element(RE). An RB includes 12×7 REs. The number of RBs in a DL slot, NDLdepends on a DL transmission bandwidth. The structure of the uplink slotmay be the same as the structure of the downlink slot.

FIG. 4 illustrates a structure of a UL subframe which may be used inembodiments of the present disclosure.

Referring to FIG. 4, a UL subframe may be divided into a control regionand a data region in the frequency domain. A PUCCH carrying UCI isallocated to the control region and a PUSCH carrying user data isallocated to the data region. To maintain a single carrier property, aUE does not transmit a PUCCH and a PUSCH simultaneously. A pair of RBsin a subframe are allocated to a PUCCH for a UE. The RBs of the RB pairoccupy different subcarriers in two slots. Thus it is said that the RBpair frequency-hops over a slot boundary.

FIG. 5 illustrates a structure of a DL subframe that may be used inembodiments of the present disclosure.

Referring to FIG. 5, up to three OFDM symbols of a DL subframe, startingfrom OFDM symbol 0 are used as a control region to which controlchannels are allocated and the other OFDM symbols of the DL subframe areused as a data region to which a PDSCH is allocated. DL control channelsdefined for the 3GPP LTE system include a Physical Control FormatIndicator Channel (PCFICH), a PDCCH, and a Physical Hybrid ARQ IndicatorChannel (PHICH).

The PCFICH is transmitted in the first OFDM symbol of a subframe,carrying information about the number of OFDM symbols used fortransmission of control channels (i.e. the size of the control region)in the subframe. The PHICH is a response channel to a UL transmission,delivering an HARQ ACK/NACK signal. Control information carried on thePDCCH is called Downlink Control Information (DCI). The DCI transportsUL resource assignment information, DL resource assignment information,or UL Transmission (Tx) power control commands for a UE group.

2. New Radio Access Technology System

As more and more communication devices require greater communicationcapacity, there is a need for mobile broadband communication enhancedover existing radio access technology (RAT). In addition, massiveMachine-Type Communications (MTC) capable of providing a variety ofservices anywhere and anytime by connecting multiple devices and objectsis also considered. Communication system design considering services/UEssensitive to reliability and latency is also under discussion.

Thus, introduction of a new radio access technology considering enhancedmobile broadband communication, massive MTC, and Ultra-Reliable and LowLatency Communication (URLLC) is being discussed. In the presentinvention, for simplicity, this technology will be referred to as NewRAT.

2.1. Self-Contained Subframe Structure

FIG. 6 is a diagram illustrating a self-contained subframe structureapplicable to the present invention.

In the New RAT system to which the present invention is applicable, aself-contained subframe structure as shown in FIG. 6 is proposed inorder to minimize data transmission latency in the TDD system.

In FIG. 6, the hatched region (e.g., symbol index=0) represents adownlink control region, and the black region (e.g., symbol index=13)represents an uplink control region. The other region (e.g., symbolindex=1 to 12) may be used for downlink data transmission or for uplinkdata transmission.

In this structure, DL transmission and UL transmission may besequentially performed in one subframe. In addition, DL data may betransmitted and received in one subframe and UL ACK/NACK therefor may betransmitted and received in the same subframe. As a result, thisstructure may reduce time taken to retransmit data when a datatransmission error occurs, thereby minimizing the latency of final datatransmission.

In such a self-contained subframe structure, a time gap having a certaintime length is required in order for the base station and the UE toswitch from the transmission mode to the reception mode or from thereception mode to the transmission mode. To this end, some OFDM symbolsat the time of switching from DL to UL in the self-contained subframestructure may be set as a guard period (GP).

While a case where the self-contained subframe structure includes boththe DL control region and the UL control region has been describedabove, the control regions may be selectively included in theself-contained subframe structure. In other words, the self-containedsubframe structure according to the present invention may include notonly the case of including both the DL control region and the UL controlregion but also the case of including either the DL control region orthe UL control region alone as shown in FIG. 6.

For simplicity of explanation, the frame structure configured as aboveis referred to as a subframe, but this configuration can also bereferred to as a frame or a slot. For example, in the New RAT system,one unit consisting of a plurality of symbols may be referred to as aslot. In the following description, a subframe or a frame may bereplaced with the slot described above.

2.2. OFDM Numerology

The New RAT system uses the OFDM transmission scheme or a similartransmission scheme. Here, the New RAT system may typically have theOFDM numerology as shown in Table 2.

TABLE 2 Parameter Value Subcarrier-spacing (Δf) 75 kHz OFDM symbollength 13.33 μs Cyclic Prefix(CP) length 1.04 us/0.94 μs System BW 100MHz No. of available subcarriers 1200 Subframe length 0.2 ms Number ofOFDM symbol per Subframe 14 symbols

Alternatively, the New RAT system may use the OFDM transmission schemeor a similar transmission scheme, and may use an OFDM numerologyselected from among multiple OFDM numerologies as shown in Table 3.Specifically, as disclosed in Table 3, the New RAT system may take the15 kHz subcarrier-spacing used in the LTE system as a base, and use anOFDM numerology having subcarrier-spacing of 30, 60, and 120 kHz, whichare multiples of the 15 kHz subcarrier-spacing.

In this case, the cyclic prefix, the system bandwidth (BW) and thenumber of available subcarriers disclosed in Table 3 are merely anexample that is applicable to the New RAT system according to thepresent invention, and the values thereof may vary depending on theimplementation method. Typically, for the 60 kHz subcarrier-spacing, thesystem bandwidth may be set to 100 MHz. In this case, the number ofavailable subcarriers may be greater than 1500 and less than 1666. Also,the subframe length and the number of OFDM symbols per subframedisclosed in Table 3 are merely an example that is applicable to the NewRAT system according to the present invention, and the values thereofmay vary depending on the implementation method.

TABLE 3 Parameter Value Value Value Value Subcarrier-spacing (Δf) 15 kHz30 kHz 60 kHz 120 kHz OFDM symbol length 66.66 33.33 16.66 8.33 CyclicPrefix(CP) 5.20 μs/4.69 μs 2.60 μs/2.34 μs 1.30 μs/1.17 μs 0.65 μs/0.59μs length System BW 20 MHz 40 MHz 80 MHz 160 MHz No. of available 12001200 1200 1200 subcarriers Subframe length 1 ms 0.5 ms 0.25 ms 0.125 msNumber of OFDM 14 symbols 14 symbols 14 symbols 14 symbols symbol perSubframe

2.3. Analog Beamforming

In a millimeter wave (mmW) system, since a wavelength is short, aplurality of antenna elements can be installed in the same area. Thatis, considering that the wavelength at 30 GHz band is 1 cm, a total of100 antenna elements can be installed in a 5*5 cm panel at intervals of0.5 lambda (wavelength) in the case of a 2-dimensional array. Therefore,in the mmW system, it is possible to improve the coverage or throughputby increasing the beamforming (BF) gain using multiple antenna elements.

In this case, each antenna element can include a transceiver unit (TXRU)to enable adjustment of transmit power and phase per antenna element. Bydoing so, each antenna element can perform independent beamforming perfrequency resource.

However, installing TXRUs in all of the about 100 antenna elements isless feasible in terms of cost. Therefore, a method of mapping aplurality of antenna elements to one TXRU and adjusting the direction ofa beam using an analog phase shifter has been considered. However, thismethod is disadvantageous in that frequency selective beamforming isimpossible because only one beam direction is generated over the fullband.

To solve this problem, as an intermediate form of digital BF and analogBF, hybrid BF with B TXRUs that are fewer than Q antenna elements can beconsidered. In the case of the hybrid BF, the number of beam directionsthat can be transmitted at the same time is limited to B or less, whichdepends on how B TXRUs and Q antenna elements are connected.

FIGS. 7 and 8 are diagrams illustrating representative methods forconnecting TXRUs to antenna elements. Here, the TXRU virtualizationmodel represents the relationship between TXRU output signals andantenna element output signals.

FIG. 7 shows a method for connecting TXRUs to sub-arrays. In FIG. 7, oneantenna element is connected to one TXRU.

Meanwhile, FIG. 8 shows a method for connecting all TXRUs to all antennaelements. In FIG. 8, all antenna element are connected to all TXRUs. Inthis case, separate addition units are required to connect all antennaelements to all TXRUs as shown in FIG. 8.

In FIGS. 7 and 8, W indicates a phase vector weighted by an analog phaseshifter. That is, W is a major parameter determining the direction ofthe analog beamforming. In this case, the mapping relationship betweenCSI-RS antenna ports and TXRUs may be 1:1 or 1-to-many.

The configuration shown in FIG. 7 has a disadvantage in that it isdifficult to achieve beamforming focusing but has an advantage in thatall antennas can be configured at low cost.

On the contrary, the configuration shown in FIG. 8 is advantageous inthat beamforming focusing can be easily achieved. However, since allantenna elements are connected to the TXRU, it has a disadvantage ofhigh cost.

2.4. CSI Feedback

In the 3GPP LTE or LTE-A system, user equipment (UE) has been defined toreport channel state information (CSI) to a base station (BS or eNB).Herein, the CSI refers to information indicating the quality of a radiochannel (or link) formed between the UE and an antenna port.

For example, the CSI may include a rank indicator (RI), a precodingmatrix indicator (PMI), and a channel quality indicator (CQI).

Here, RI denotes rank information about the corresponding channel, whichmeans the number of streams that the UE receives through the sametime-frequency resource. This value is determined depending on thechannel's Long Term Fading. Subsequently, the RI may be fed back to theBS by the UE, usually at a longer periodic interval than the PMI or CQI.

The PMI is a value reflecting the characteristics of a channel space andindicates a precoding index preferred by the UE based on a metric suchas SINR.

The CQI is a value indicating the strength of a channel, and generallyrefers to a reception SINR that can be obtained when the BS uses thePMI.

In the 3GPP LTE or LTE-A system, the base station may set a plurality ofCSI processes for the UE, and receive a report of the CSI for eachprocess from the UE. Here, the CSI process is configured with a CSI-RSfor specifying signal quality from the base station and aCSI-interference measurement (CSI-IM) resource for interferencemeasurement.

2.5. RRM Measurement

LTE systems support radio resource management (RRM) operations includingpower control, scheduling, cell search, cell reselection, handover,radio link or connection monitoring, and connectionestablishment/re-establishment. In this operation, a serving cell maymake a request to a UE for RRM measurement information, which is ameasurement value for performing the RRM operation. As typicalinformation, in an LTE system, a UE may measure information such as cellsearch information on each cell, reference signal received power (RSRP),and reference signal received quality (RSRQ) and report the same astypical information. Specifically, in the LTE system, the UE may receive‘measConfig’ from the serving cell over a higher-layer signal for RRMmeasurement, and measure the RSRP or RSRQ according to the informationof ‘measConfig’.

Here, RSRP, RSRQ, and RSSI disclosed in the LTE system may be defined asfollows.

First, reference signal received power (RSRP) is defined as the linearaverage over the power contributions (in [W]) of the resource elementsthat carry cell-specific reference signals within the consideredmeasurement frequency bandwidth. For example, for RSRP determination thecell-specific reference signals R₀ shall be used. If the UE can reliablydetect that R₁ is available it may use R₁ in addition to R₀ to determineRSRP.

The reference point for the RSRP shall be the antenna connector of theUE.

If receiver diversity is in use by the UE, the reported value shall notbe lower than the corresponding RSRP of any of the individual diversitybranches.

Reference Signal Received Quality (RSRQ) is defined as the ratioN×RSRP/(E-UTRA carrier RSSI), where N is the number of RB's of theE-UTRA carrier RSSI measurement bandwidth. The measurements in thenumerator and denominator shall be made over the same set of resourceblocks.

E-UTRA Carrier Received Signal Strength Indicator (RSSI), comprises thelinear average of the total received power (in [W]) observed only inOFDM symbols containing reference symbols for antenna port 0, in themeasurement bandwidth, over N number of resource blocks by the UE fromall sources, including co-channel serving and non-serving cells,adjacent channel interference, thermal noise etc. If higher-layersignalling indicates certain subframes for performing RSRQ measurements,then RSSI is measured over all OFDM symbols in the indicated subframes.

The reference point for the RSRQ shall be the antenna connector of theUE.

If receiver diversity is in use by the UE, the reported value shall notbe lower than the corresponding RSRQ of any of the individual diversitybranches.

Next, Received Signal Strength Indicator (RSSI) is defined as thereceived wide band power, including thermal noise and noise generated inthe receiver, within the bandwidth defined by the receiver pulse shapingfilter.

The reference point for the measurement shall be the antenna connectorof the UE.

If receiver diversity is in use by the UE, the reported value shall notbe lower than the corresponding UTRA carrier RSSI of any of theindividual receive antenna branches.

In accordance with the definitions above, in the case of intra-frequencymeasurement, a UE operating in the LTE system may measure RSRP in thebandwidth indicated through the allowed measurement bandwidth-relatedinformation element (IE), which is transmitted on system informationblock type 3, in SIB3. Alternatively, in the case of inter-frequencymeasurement, the UE may measure RSRP in a bandwidth corresponding to oneof 6, 15, 25, 50, 75, and 100 resource blocks (RBs) indicated throughthe allowed measurement bandwidth transmitted in SIBS. Alternatively, inthe case where the IE is absent, the UE may measure RSRP in thefrequency band of the entire downlink (DL) system as a defaultoperation.

In this case, if the UE receives the information on the allowedmeasurement bandwidth, the UE may consider the corresponding value asthe maximum measurement bandwidth and freely measure the RSRP valuewithin the range of the corresponding value. However, if the servingcell transmits an IE defined as WB-RSRQ to the UE and the allowedmeasurement bandwidth is set to 50 RBs or more, the UE shall calculatethe RSRP value for the entire allowed measurement bandwidth. In the RSSImeasurement, the UE measures RSSI using the frequency band of thereceiver of the UE according to the definition of the RSSI bandwidth.

3. Proposed Embodiments

The present invention proposes a method for performing, by a UE, RRMmeasurement on a serving cell and a neighbor cell from which the UE isto receive data based on the RRM configuration of the LTE system when aBS implements analog beamforming which allows the base station toarbitrarily change a beam for transmitting a signal over time in awireless communication system including the BS and the UE.

In the New RAT system described above, network slicing for implementinga plurality of logical networks on a single physical network is beingdiscussed. The logical networks must be capable of supporting varioustypes of services (e.g., Enhanced Mobile Broadband (eMBB), massiveMachine Type Communication (mMTC), Ultra Reliable and Low Latency(URLLC), etc.).

In a wireless communication system (or the physical layer) of the NewRAT system, a flexible structure capable of applying an OFDM schemehaving a numerology suitable for a service to be provided is considered.In other words, in the New RAT system, an OFDM scheme (or a multipleaccess scheme) having different numerologies for respective time andfrequency resource regions is considered.

In addition, as data traffic is rapidly increasing due to the recentintroduction of smart devices, higher communication capacity (e.g., datathroughput) is required in the New RAT system.

Thus, as a method to increase the communication capacity, performingdata transmission using multiple transmit (or receive) antennas may beconsidered. In this case, applying digital beamforming to the multipleantennas requires an RF chain (e.g., a chain including RF devices suchas a power amplifier and a down converter) and a D/A (or A/D) converter(i.e., a digital-to-analog or analog to digital converter), which maycause high hardware complexity and high power consumption, and thereforemay not be practical.

Accordingly, when multiple antennas are used in a New RAT system towhich the present invention is applicable, a hybrid beamformingtechnique of employing both digital beamforming and analog beamformingis considered. Herein, analog beamforming (or RF beamforming) refers toan operation of precoding (or combining) at the RF stage.

In the hybrid beamforming structure, precoding (or combining) isperformed at the baseband stage and the RF stage, respectively, andtherefore the number of RF chains and the number of D/A (or A/D)converters may be reduced, while achieving performance close to digitalbeamforming.

For simplicity of explanation, when the hybrid beamforming structure isrepresented by N transceiver units (TXRUs) and M physical antennas,digital beamforming for L data layers to be transmitted by thetransmission end may be represented by an N*L matrix, and the Nconverted digital signals obtained thereafter may be converted intoanalog signals via the TXRUs and then subjected to analog beamforming,which is represented by an M*N matrix.

FIG. 9 is a diagram schematically illustrating a hybrid beamformingstructure from the perspective of a TXRU and physical antennas. In FIG.9, the number of digital beams is L and the number of analog beams is N.

Further, in the New RAT system, a method for supporting more efficientbeamforming for a UE located in a specific area by designing the basestation so as to change the analog beamforming on a symbol-by-symbolbasis is being considered. In this case, when the base station utilizesa plurality of analog beams as described above, the analog beamsadvantageous for signal reception may differ from UE to UE, andtherefore the base station may transmit at least a synchronizationsignal, system information, paging, and the like through differentanalog beams on respective symbols in a specific subframe (SF). Thereby,all UEs may have an opportunity to receive the synchronization signal,the system information and the paging in the specific SF. Such anoperation may be called beam sweeping.

FIG. 10 is a diagram schematically illustrating a beam sweepingoperation for a synchronization signal and system information in adownlink transmission procedure. For reference, in FIG. 10, a physicalresource (or physical channel) on which the system information of theNew RAT system is transmitted is called an xPBCH in order to bedistinguished from the physical broadcast channel (PBCH) of the LTEsystem.

In FIG. 9, when N specific TXRUs and M RF antennas are defined as oneantenna panel, a plurality of antenna panels to which independent hybridbeamforming is applicable may be employed in the New RAT system to whichthe present invention is applicable. In this case, there may be as manyanalog beams as the antenna panels in one symbol. For simplicity ofexplanation, analog beams capable of being simultaneously transmittedwithin one symbol (or one time unit) are referred to as an analog beamgroup.

Given such an analog beam group, a beam reference signal (BRS), which isa reference signal transmitted by applying each analog beam, may beconsidered as shown in FIG. 10. Through the BRS, the UE may measurechannels for each analog beam.

At this time, unlike the BRS, the synchronization signal or the PBCH maybe transmitted by applying all the analog beams in the analog beam groupsuch that the synchronization signal or the PBCH may be well received byall UEs.

Similarly to the above case, channels need to be measured in the New RATsystem for the purpose of RRM, and therefore it is necessary to defineresources to form the basis of RRM measurement. Accordingly, the presentinvention proposes a method of RRM measurement in consideration of theanalog beam group in the New RAT system. Hereinafter, as conceptscorresponding to the RSRP, RSSI, and RSRQ of the LTE system, the averagereceived power (per resource element) for a specific measurementresource for use in RRM measurement in the New RAT system is defined asxRSRP, the average received power considering all signals in a symbol isdefined as xRSSI, and an index indicating the relative ratio betweenxRSRP and xRSSI is defined as xRSRQ (i.e., xRSRQ∝xRSRP/xRSSI).

Hereinafter, an RS (or known signal) used for RRM measurement will bereferred to as an RRM RS, and a point that performs DL/UL transmissionto the UE will be referred to as a transmission and reception point(TRP). Here, the TRP may correspond to a specific physical cell, aplurality of physical cell groups or a specific analog beam.

In addition, in the description of the present invention, the antennaport refers to a virtual antenna element for which the same channelcharacteristics (e.g., delay profile, Doppler spread, etc.) may beassumed (at least in the same resource block).

In addition, a synchronization signal (SS) refers to a reference signalused for a UE to perform time synchronization for atransmission/reception operation with respect to a specific TRP, and asubframe (SF) refers to a transmission unit with a certain length oftime that is repeated, wherein definition of the SF may be varied amongnumerologies.

The configuration information that a TRP delivers to a UE for RRMmeasurement through higher-layer signaling or the like is referred to asmeasurement configuration. The measurement configuration may include aTRP index (to be measured), resource allocation information and sequenceinformation about the RRM RS, and a bandwidth for RRM measurement.

Hereinafter, configurations for RRM measurement applicable to the NewRAT system will be described in detail based on the description above.

3.1. Methods for Configuring RRM RS

3.1.1. First Method for Configuring RRM RS

When RRM measurement is performed (for a specific TRP), the UE may nothave a separate measurement configuration for the TRP or may not receivethe measurement configuration. In this case, the UE may assumetransmission of an RRM RS (where the transmitted RRM RS is calledType 1) as one of the following. Alternatively, the base station maytransmit an RRM RS for the UE as one of the following.

(1) The UE assumes that the RRM RS is transmitted in a (pre-agreed)frequency resource region in an SF in which the Sync Signal (SS) hasbeen transmitted. In other words, the base station may transmit the RRMRS through a certain frequency resource region within the SF in whichthe SS has been transmitted. In this case, it is assumed that thenumerology of the RRM RS is applied in the same way as that of the SS.

(2) The UE assumes that the RRM RS is transmitted in a (pre-agreed)frequency resource region in an SF implied from the SF in which the SShas been transmitted. In other words, the base station may transmit theRRM RS through a certain frequency resource region within an SF impliedfrom the SF in which the SS has been transmitted.

(3) The UE assumes that the RRM RS is transmitted in a pre-agreed SF andin a (pre-agreed) frequency resource region. In other words, the basestation may transmit the RRM RS through a specific frequency resourceregion in a specific SF. In this case, it is assumed that the defaultnumerology is applied as the numerology of the RRM RS.

Here, the sequence information and the time and frequency resourceinformation about the RRM RS (Type 1) may be determined as a function ofa unique ID of a corresponding TRP (that transmits the RRM RS), ananalog beam index value and/or the indexes of the time and frequencyresources in which the SS is transmitted. In other words, the sequenceinformation and the time/frequency resource information about the RRM RSmay be determined as a function of (the unique ID of the correspondingTRP, the analog beam index value), (the unique ID of the correspondingTRP, the indexes of the time/frequency resources in which the SS istransmitted), or (the unique ID of the corresponding TRP, the analogbeam index value, and the indexes of the time/frequency resources inwhich the SS is transmitted).

However, in the foregoing description, the default numerology may bedetermined according to a frequency band in which the TRP is operated,and it may be assumed that the beam sweeping operation is applied in atleast a specific frequency band within a pre-agreed SF.

More specifically, in order for the UE to measure the received power (orxRSRP) of the RRM RS based on the RRM RS, the UE must be aware of theresource region through which the RRM RS is transmitted in advance. Inthis case, considering that the UE must be capable of performing RRMmeasurement on the TRPs which may become the targets of handover inaddition to the TRP from which the UE is to be provided with a service,RRM RS resources on which the UE may perform RRM measurement even in acase where it is difficult to ensure that the UE receives systeminformation (e.g., a TRP is at a relatively long distance) need to bedefined separately.

Accordingly, it may be desirable for the base station to transmit an RRMRS conforming to a pre-agreed numerology on time and frequency resourceswhich may be known at least to the UE.

Accordingly, the UE to which the present invention is applicable mustperform at least synchronization with respect to the TRP on which theRRM measurement is to be performed. Therefore, the UE may be configuredto expect transmission of an RRM RS in an SF in which the SS has beentransmitted or a time period implied by the SF in which the SS has beentransmitted. Accordingly, the base station to which the presentinvention is applicable may transmit the RRM RS in the SF in which theSS has been transmitted or a time period implied by the SF in which theSS has been transmitted.

Considering that an analog beam group may be changed on asymbol-by-symbol basis, which is another feature of the New RAT system,the UE to which the present invention is applicable may measure thereceived power (or xRSRP) of the RRM RS such that potential analog beamgroups that are applicable in a specific TRP are equally reflected.

For example, suppose that the received power of a signal received by UE1 from specific TRP 1 through analog beam group A is high and thereceived power of a signal received through analog beam group B is low.If TRP 1 is currently transmitting the RRM RS to UE 2 through analogbeam group B, and UE 1 calculates the received power (or xRSRP) of theRRM RS by measuring the received power intensity for a specific RRM RSresource at any SF and symbol positions, only the received power foranalog beam group B will be reflected in the measured value, andtherefore the received power (or xRSRP) of the RRM RS will be reportedto be low. However, in reality, this operation may not be preferable inthat high received power may have been guaranteed if TRP 1 transmittedthe signal to UE 1 through analog beam group A.

Accordingly, the UE according to the present invention may measure theRRM RS in an SF (or time resource) in which all analog beam groups thata specific TRP can potentially use may be observed. For example, in theNew RAT system to which the present invention is applicable, UEs maymeasure the received power (or xRSRP) of the RRM RS on the assumptionthat beam sweeping is applied in a pre-agreed SF. Accordingly, in orderto measure the RRM based on the RRM RS (type 1) described above, a UEaccording to the present invention may utilize the SS of FIG. 10, theDM-RS or BRS of the xPBCH or a pre-agreed periodic RS resource.

3.1.2. Second Method for Configuring RRM RS

Unlike the case of the first method for configuring RRM RS describedabove, when the UE performs RRM measurement (on a specific TRP), theremay be a separate measurement configuration for the TRP. In this case,the UE may assume transmission of the RRM RS (where the transmitted RRMRS is called Type 2) as follows.

Specifically, the UE assumes that the RRM RS is transmitted in aspecific SF and a specific frequency resource indicated by themeasurement configuration. In other words, the base station may transmitthe RRM RS through a specific SF and specific frequency resourceindicated by the measurement configuration. However, it is assumed thatthe numerology of the RRM RS is a value set in the measurementconfiguration.

Here, the sequence information and the time and frequency resourceinformation about the RRM RS (Type 2) may be determined as a function ofthe unique ID of the corresponding TRP and the analog beam index value,or may be indicated by the measurement configuration.

In addition, the RRM RS (Type 2) may be divided into an RRM RS (Type2-1) having a periodic transmission opportunity and an RRM RS (Type 2-2)having an aperiodic transmission opportunity.

The second method for configuring the RRM RS proposed by the presentinvention will be described in detail. As described above, the New RATsystem to which the present invention is applicable is intended toflexibly provide various services such as eMBB, mMTC, and URLLC.

Here, the requirements for RRM measurement to be satisfied may differfrom service to service. For example, URLLC, where reliability isimportant, may require faster and more accurate RRM measurement than theother services. In this respect, in the New RAT system to which thepresent invention is applicable, the capability of supporting RRMmeasurement specialized for each service provided to the UE is needed.

Accordingly, the present invention proposes a method for receiving, by aUE, configuration of an RRS RS (type 2) through measurementconfiguration information (information including a transmission resourceregion (i.e., a time period and a subband) and the applied numerology asinformation about the RRS RS resources), which is configurationinformation related to measurement, from a TRP when the UE is connectedto at least one TRP.

Herein, the RRM RS (Type 2) may be configured through a higher-layersignal, and Type 2-1 which is periodically transmitted based on theconfiguration information may be applied as the RRM RS. Alternatively,the RRM RS may be transmitted only when RRM RS transmission according toa specific measurement configuration is indicated through theadditionally received dynamic control information (DCI) among theplurality of measurement configurations configured through thehigher-layer signal.

In addition, in the first RRM RS configuration method and the second RRMRS configuration method described above, the intra-SF symbol positionand the frequency resource allocation scheme for the RRM RS may dependon the RRM RS type. As an example, an RRM RS (Type 1) may be transmittedon a symbol on which the SS has been transmitted in an SF in which theSS has been transmitted. An RRM RS (Type 2) may be transmitted only onsome pre-agreed symbols within an SF in which RRM RS transmission isexpected.

3.1.3. Third method for configuring RRM RS

When the UE performs RRM measurement (on a specific TRP), the UE maydetermine whether an RRM RS (Type 1 or Type 2) is actually present in anSF (an SF in which the RRM RS transmission is assumed) using one of thefollowing methods.

(1) The UE assumes that the RRM RS is always present.

(2) The UE assumes that the RRM RS is present if the SF is a DL SF.

(3) The UE assumes that the RRM RS is present if another known signal(e.g., SS) is detected.

(4) The UE determines whether the RRM RS is present by blind detection(BD).

(5) The UE receives an indication of whether an RRM RS is presentthrough dynamic control information (DCI), and determines whether an RRMRS is present based on the indication.

(6) The UE assumes that there is an aperiodic RRM RS in an SF for whichaperiodic RRM RS transmission or aperiodic RRM measurement is indicated.

Next, if the UE determines that the RRM RS has been transmitted throughthe methods described above, the UE may utilize the corresponding RRM RSresource for RRM measurement.

Here, the method of determining whether the RRM RS is present may beapplied differently for the RRM RS (Type 1) and the RRM RS (Type 2).

More specifically, considering the dynamic characteristics of datatraffic, data traffic on DL and data traffic on UL may be generated atany point in time. In an advanced system, such as the New RAT system towhich the present invention is applicable, flexible DL/UL traffic may beconsidered in order to increase the efficiency of resource utilization.Accordingly, a specific DL may support a flexible DL/UL SF structurewhich is not fixed to DL or UL.

In this case, the SF in which the UE has expected RRM RS transmission asin the first or second RRM RS configuration method described above maybe used not as a DL SF but as a UL SF in reality, and thus the RRM RSmay not be transmitted. Therefore, when the flexible DL/UL SF structureis supported, the UE according to the present invention should becapable of determining whether or not the RRM RS is actually transmittedin an SF where RRM RS transmission is expected.

Accordingly, the UE may determine whether the RRM RS is actuallytransmitted through the various methods described above. For example, ifan SF in which RRM RS transmission is expected is actually used as a DLSF, the UE may assume that an RRM RS is transmitted in the SF asdescribed in method (2) above.

3.1.4. Fourth method for configuring RRM RS

When a specific TRP is allowed to transmit an RRM RS by applying one ofa plurality of numerologies, the specific TRP may generate an RRM RSsequence (e.g., [S₀, S₁, . . . , S_(L)]) in the frequency domain basedon the default numerology. An RRM RS sequence for a numerology havingsubcarrier spacing which is 1/N times the subcarrier spacing of thedefault numerology (where N is a positive integer) may be generated byinserting N−1 samples of zero's between frequency samples of the RRM RSsequence generated based on the default numerology (e.g., [S₀, 0, . . ., 0, S₁, 0, . . . , S_(L−1), 0, . . . , 0, S_(L)], i.e., N−1 0's areinserted between S_(k) and S_(k+1)).

Accordingly, an RRM RS sequence generated based on the defaultnumerology may be applied to a numerology having subcarrier spacingwhich is N times the subcarrier spacing of the default numerology (whereN is a positive integer) while maintaining the same subcarrier spacing.

Here, the default numerology may be determined according to thefrequency band in which the TRP is operated. In addition, the UE mayreceive the RRM RS on the assumption of the default numerology for theRRM RS irrespective of the numerology actually applied in the TRP (e.g.,the Fast Fourier Transform window section, the sampling rate, and thelike may be set on the assumption of the default numerology).

More specifically, in a case where a plurality of numerologies issupported in the New RAT system to which the present invention isapplicable, the plurality of numerologies may be supported by applyingscaling to subcarriers or symbol lengths considering ease ofimplementation.

For example, it is assumed that the system band is the same fordifferent numerologies, but the subcarrier spacings are multiples of asubcarrier spacing as in the case of 15 kHz and 30 kHz. In this case,according to the fourth RRM RS configuration method described above,subcarrier spacing of 30 kHz may be assumed as the default numerology,and an RRM RS having L samples on the frequency axis may be defined as[X₀, X₁, X₂, . . . , X_(L−1)] based on this assumption. Then, an RRM RSfor the numerology having subcarrier spacing of 15 kHz may be generatedas [X₀, 0, X₁, 0, X₂, . . . , 0, X_(L−1)] by inserting one sample of 0(zero) between frequency samples of the RRM RS sequence generated basedon the default numerology.

FIG. 11 is a diagram illustrating RRM RSs that can be defined fornumerologies having subcarrier spacings which are 1 times, ½ times, ⅓times, and ¼ times the subcarrier spacing of the default numerology.

In FIG. 11, when the subcarrier spacing applied to numerology 0 is 60kHz, it may be assumed that a subcarrier spacing of 30 kHz is applied tonumerology 1, a subcarrier spacing of 20 kHz is applied to numerology 2,and a subcarrier spacing of 15 kHz is applied to numerology 3. As shownin FIG. 11, the RRM RS sequence generated on the basis of the defaultnumerology may be applied even to a numerology having a subcarrierspacing which is N times the subcarrier spacing of the defaultnumerology (wherein N is a positive integer) while maintaining the samesubcarrier spacing and the same relative resource positions on thefrequency axis in the system band.

In addition, considering Numerology X having subcarrier spacing which isN times the subcarrier spacing of the default numerology, the UEaccording to the present invention may perform RRM measurement using anRRM RS on the assumption that the RRM RS is transmitted only on a symbolentirely included in a specific symbol in a Numerology X-based SF amongthe symbols in a default numerology-based SF.

FIG. 12 is a diagram illustrating a case where the subcarrier spacing ofthe default numerology is 30 kHz and the subcarrier spacing ofNumerology X is 15 kHz. Here, as shown in FIG. 12, it is assumed thatthe symbol configuration in one SF differs from one numerology toanother.

When the UE performs RRM measurement on a neighbor TRP, it may bedifficult to determine which numerology is currently applied by thecorresponding TRP because it is difficult to receive separateinformation from the corresponding TRP. In this regard, the UE mayattempt to receive the RRM RS based on the default numerology,irrespective of the numerology actually used by a TRP, as in the fourthRRM RS configuration method described above.

However, if the FFT window section in which the default numerology isassumed is not completely included in a symbol on which the TRP actuallyperforms transmission, the UE may not properly receive the RRM RS.Therefore, the UE according to the present invention may assume that anRRM RS (conforming to the fourth RRM RS configuration method) istransmitted only on symbols completely included in a specific symbol inan SF defined on the assumption of Numerology X among the symbols in anSF defined on the assumption of the default numerology.

In the example of FIG. 12, Symbols #0 and #1 given when the defaultnumerology is assumed are included in Symbol #0 given when Numerology Xis assumed, and therefore the TRP according to the present invention maytransmit the RRM RS in Symbols #0 and #1 given when the defaultnumerology is assumed. In response, the UE according to the presentinvention may assume that the RRM RS conforming to proposed method #4 istransmitted in Symbols #0, #1, #3, #5, #8, #12, and #13 given when thedefault numerology is assumed.

However, at least the SF (or slot) boundaries for the default numerologyand Numerology X (i.e., a numerology with subcarrier spacing which is1/N times the subcarrier spacing of the default numerology or any othernumerology supported by the TRP) may be designed to coincide with eachother.

In this case, the base station may notify the UE receiving the dataservice therefrom, through a higher-layer signal (e.g., RRC signaling)or a dynamic control signal (e.g., DCI), that data rate matching hasbeen applied to the time and frequency resources in which the RRM RS istransmitted or that data rate matching has been applied to (some or all)REs on which the RRM RS is transmitted. In addition, the network maynotify UEs to use the RRM RS of the time and frequency resourceinformation about the RRM RS through a higher-layer signal such as RRCsignaling. At this time, the information about the numerology applied tothe RRM RS may be delivered by applying the default numerology that hasgenerated the RRM RS. A UE that performs RRM measurement using the RRMRS may assume a constantly transmitted RRM RS transmission symbolaccording to the network configuration information. In reality, if 1/Ntime numerology is applied and an RRM RS transmission symbol (given whenthe default numerology is assumed) is repeated N times, the UE maydetermine whether or not the RRM RS transmission symbols repeated Ntimes are present based on the received power in an RRM RS transmissionsymbol in which there is always a transmission, and utilize thedetermination for the RRM RS.

The method described above may be applied not only to the RRM RS butalso to a reference signal (RS) or an SS that may be transmitted byapplying a plurality of numerologies.

In the first RRM RS configuration method and the fourth RRM RSconfiguration method described above, a plurality of defaultnumerologies may be defined. In this case, the UE may detect an actuallyapplied default numerology through blind detection, or determine thesame through separate system information.

3.1.5. Fifth Method for Configuring RRM RS

If a TRP according to the present invention is capable of transmittingan RRM RS for a maximum of N antenna ports on orthogonal resources forthe respective antenna ports, the TRP may apply analog beamforming tothe antenna ports of the RRM RS according to one of the followingmethods:

(1) Apply the same analog beamforming group (or analog beam) to all theantenna ports for the RRM RS;

(2) Apply an independent analog beam for each of the antenna ports forthe RRM RS.

Here, the TRP may always allocate frequency resources and sequences ofRRM RSs to each antenna port, assuming a maximum number of antenna ports(N) (or a pre-agreed number of antenna ports).

In case of the RRM RS (Type 2), the base station or the TRP may informthe UE of the analog beamforming scheme applied to the RRM RS throughmeasurement configuration.

In addition, when the RRM RS is transmitted in L (L>1) symbols in an SF,the analog beam group (or analog beam) applied to each antenna port maydiffer from symbol to symbol.

More specifically, considering analog beamforming, which is one of thefeatures of the New RAT system to which the present invention isapplicable, how to apply analog beamforming for each antenna portthrough which the RRM RS is transmitted may raise an issue.

Accordingly, when the UE does not perform RRM measurement on the basisof a single analog beam but performs RRM measurement on the basis of ananalog beam group (as in the case of, for example, RRM measurement on aneighbor cell, a neighbor TRP, or the like), the UE may apply the sameanalog beam group (or analog beam) to all antenna ports for the RRM RSand then measure the RRM RS received power (or xRSRP) using some or allantenna ports for the RRM RS. Specifically, the UE may apply anaggregated analog beam formed by aggregating a plurality of analog beamsin specific analog beam group A to the RRM RS for analog beam group A.

In the New RAT system to which the present invention is applicable, atleast the SS and xPBCH expected to be received by a UE may be expectedto be transmitted by applying all the analog beams in the analog beamgroup (i.e., through an aggregated analog beam). Thus, according to thepresent invention, DM-RS resources in the SS or xPBCH may be consideredas the resources for xRSRP measurement for each analog beam group.

Alternatively, the base station according to the present invention mayinstruct the UE to perform RRM measurement for each analog beam. Forexample, the TRP may instruct the UE to measure RRM RS received power(or xRSRP) for each specific analog beam, using the BRS of FIG. 10. Inmore general terms, the TRP may transmit the RRM RS for a maximum of Nantenna ports on orthogonal resources for each antenna port, and the RRMRS for each antenna port may be transmitted through a specific analogbeam.

At this time, in order to enable the UE to utilize the RRM RStransmitted to the plurality of antenna ports in RRM measurement evenwithout additional system information (or configuration information),the TRP may always allocate frequency resources and sequences of the RRMRS to each antenna port, assuming the maximum antenna port number (forexample, N). The BRS resources of FIG. 10 may be used as resources forRRM RS received power (or xRSRP) measurement for each analog beam.

3.2. Method for Measuring and Reporting RRM RS Received Power

In this section, a method for measuring and reporting received powerusing the RRM RS is described for simplicity of explanation, but theelements described below may be extended to any RRM measurement objects.

3.2.1. First Method for Measuring and Reporting RRS RS Received Power

If a specific TRP is capable of transmitting an RRM RS for a maximum ofN antenna ports in orthogonal resources for each antenna port, the UEaccording to the present invention may measure and report RRM RSreceived power using one of the following methods.

(1) The UE may measure and report the (single) RRM RS received powerreceived through (pre-agreed) specific antenna port(s).

(2) The UE may measure and report the RRM RS received power for eachantenna port, assuming the maximum number of antenna ports (e.g., N) (ora pre-agreed number of antenna ports).

Here, the TRP always defines an RRM RS (e.g., BRS) resource (e.g., afrequency-axis resource and a sequence) for each antenna port on theassumption of a maximum number of antenna ports (or a pre-agreed numberof antenna ports) for the RRM RS and it is assumed that only the RRM RS(e.g., BRS) resources corresponding to the number of antenna ports whichare actually used are allowed for transmission.

More specifically, in the New RAT system to which the present inventionis applicable, the RRM RS received power (or xRSRP) measurement methodof the UE may be changed depending on the manner in which the TRPapplies analog beamforming to the RRM RS. If the UE assumes that ananalog beam group (or an aggregated analog beam) is applied to the RRMRS, the UE may measure the RRM RS received power (or xRSRP) using onlyspecific antenna port(s) pre-agreed for the RRM RS.

In measuring the RRM RS received power for each antenna port, the UE maymeasure the RRM RS received power assuming the maximum number of antennaports. For example, in supporting BRS transmission in the New RAT systemas shown in FIG. 10, an operation in which the UE measures the RRM RSreceived power (or xRSRP) for each single analog beam using the BRS maybe considered.

However, when the UE intends to measure the RRM RS received power (orxRSRP) for a neighbor TRP (or neighbor cell), reception of the systeminformation from the corresponding TRP (or cell) may not be ensured.Accordingly, there may be a case where the UE cannot know the RRM RS(e.g., BRS) information about a specific neighbor TRP (or neighborcell).

Therefore, in order to address the issue as above, the present inventionproposes a method for measuring, by the UE, RRM RS received power (orxRSRP) for each analog beam using an RRM RS (e.g., BRS) even if the UEdoes not know the RRM RS (e.g., BRS) information about a TRP (or cell)for which the UE intends to measure the RRM RS received power (orxRSRP).

As a simple solution to the aforementioned issue, the TRP may alwaysdefine an RRM RS (e.g., BRS) resource assuming the maximum number ofantenna ports.

FIG. 13 is a diagram schematically illustrating a BRS for each antennaport from the perspective of a UE or a base station.

As shown in FIG. 13, when the number of antenna ports available foractual BRS transmission is one, two, four, or eight, the base station orthe TRP may always define BRS resources (e.g., a frequency-axis resourceand sequence) for each antenna port which are transmitted every eightREs assuming a maximum of eight antenna ports. Thus, the UE may assumeBRS resources for each antenna port as shown in FIG. 13.

In FIG. 13, different sequences may be applied for REs, respectively. Atthis time, as shown in FIG. 13, the base station may leave a BTSresource for an antenna port not used for actual BRS transmission blank.

If the base station desires to transmit an additional RS for antennaport X in a resource corresponding to another antenna port Y (≠X), itmay apply the same analog beam as for antenna port X but use an RRM RS(e.g., BRS) resource (e.g., a frequency resource and sequence)corresponding to antenna port Y.

FIG. 14 is a diagram schematically illustrating a configuration fortransmitting an additional RS for BRS antenna port 0 in the example ofFIG. 13 in resources corresponding to antenna ports 1, 2, 3, . . . , 7through the same analog beam. In FIG. 14, different patterns forresource elements (REs) mean that different sequences are applied.

When the UE measures the RRM RS received power for each antenna port,the UE may measure the RRM RS received power (or xRSRP) for each RRM RS(e.g., BRS) resource corresponding to each antenna port on theassumption of the maximum number of antenna ports for the RRM RS (e.g.,BRS) and report as many RRM RS received power measurement values (orxRSRP) as the maximum number of antenna ports to the base station.

In an exemplary embodiment of the present invention, the operation ofthe UE measuring the RRM RS received power for each antenna to beapplied only when the RRM RS received power (or xRSRP) for a neighborTRP (or neighbor cell) belonging to a specific TRP group (cell group)(e.g., a cooperative cell group) configured by the serving TRP ismeasured. At this time, for the neighbor TRPs (or neighbor cells) notbelonging to the TRP group (or the cell group), the UE may measure onlythe RRM RS received power (or xRSRP) received at (pre-agreed) specificantenna port(s).

Here, the RRM RS resources that the UE uses to perform RRM measurementon the serving TRP may be distinguished from the RRM RS resources thatthe UE uses to perform RRM measurement on the neighbor TRPs. Forexample, a BRS for which a single analog beam is applicable to eachantenna port may be used as an RRM RS in order to perform RRMmeasurement on the serving TRP, and an SS or a DM-RS of xPBCH to whichan analog beam group (or an aggregated analog beam) is applied may beused as an RRM RS in order to perform RRM measurement on a neighbor TRP.

In addition, in measuring the RRM RS received power for each antennaport according to the proposed method, the UE may measure the averageRRM RS received power for all symbols in which the RRM RS istransmitted, without differentiating analog beam groups (or analogbeams) applied to the respective symbols.

3.2.2. Second Method for Measuring and Reporting RRM RS Received Power

When up to L independent analog beam groups (or analog beams) areallowed to be alternately applied on L symbols in an SF in which a UEwill measure RRM RS received power from the perspective of a specificTRP, the UE may measure and report the RRM RS received power using oneof the following methods, wherein the one method may be a pre-agreedmethod or a method indicated by the TRP:

(1) Measure and report RRM RS received power for each combination of(pre-agreed) antenna port(s) and symbol index;

(2) Measure and report RRM RS received power for each combination ofantenna port and symbol index assuming a maximum number of antenna ports(or a pre-agreed number of antenna ports).

Herein, if the UE can receive the configuration information about RRMmeasurement, the TRP may instruct the UE to follow one of the first orsecond RRM RS received power measurement methods proposed above.

As a concrete example, in the New RAT system applicable to the presentinvention as in the first RRM RS configuration method described above,the UE may measure RRM RS received power (or xRSRP) by fairly reflectingthe analog beam groups potentially usable by a specific TRP (or cell).To this end, the UE may measure RRM RS received power (or xRSRP) in anSF in which the operation of alternately applying analog beam groupsapplicable by the corresponding TRP (or cell) on each symbol is applied(i.e., an SF in which beam sweeping is applied).

Here, it is assumed that different analog beam groups can be applied onthe respective symbols in the SF in which beam sweeping is applied.Then, when the UE measures the RRM RS received power (or xRSRP) on theanalog beam group basis, the UE may calculate the average received powerof measurement resources for RRM RS received power (or xRSRP) forrespective symbols to which the same analog beam group is applied in anSF in which RRM RS received power (or xRSRP) is to be measured. Then,the UE may report the RRM RS received power for each symbol to theserving TRP thereof.

3.2.3. Third Method for Measuring and Reporting RRS RS Received Power

In a case where RRM RS received power is measured with a plurality ofRRM RS types configured for a UE, the UE according to the presentinvention may measure and report the RRM RS received power according toone of the following methods:

(1) Independent measurement and reporting for each RRM RS type;

(2) Applying a weight to a specific RRM RS type while measuring a singlevalue irrespective of the RRM RS type.

Herein, the RRM RS type may refer to a specific RRM RS transmissionformat defined according to RRM RS transmission resources or sequence ora triggering method for indicating RRM RS transmission. In addition, aweight for a specific RRM RS type may be pre-agreed or may be deliveredto the UE through a higher-layer signal or DCI.

As a specific example, suppose that there is an RRM RS (Type 2)configurable by the serving TRP as in the second RRM RS configurationmethod described above. More specifically, suppose that there are aperiodically transmittable RRM RS (Type 2-1) and an RRM RS (type 2-2),transmission of which is aperiodically instructed by a TRP. In thiscase, the TRP may instruct the UE to measure and report independent RRMRS received power for each RRM RS type or may instruct the UE to measureand report RRM RS received power of a single value using all RRM RStypes configured for the UE.

In the latter case, the UE may assign and apply a higher weight to theRRM RS (type 2-2) in measuring the RRM RS received power, assuming ordetermining that the RRM RS (type 2-2) is a RRM RS resource exhibitinghigher accuracy. Alternatively, as described above, a value indicated bythe base station or the TRP may be applied as the weight.

3.3. Method for Measuring and Reporting In-Symbol Received Power

The “in-symbol received power” described in this section may mean thetotal received power of a signal received within a symbol.

3.3.1. First Method for Measuring and Reporting in-Symbol Received Power

In measuring in-symbol received power (e.g., xRSSI) (for a specificTRP), the UE may measure in-symbol received power (e.g., xRSSI) for eachof K analog beam groups (or analog beams) using only a signal to whichthe corresponding analog beam group (or analog beam) and report RRMinformation (e.g., an xRSSI value or xRSRQ utilizing xRSSI). In otherwords, the UE may measure and report a total of K xRSSIs.

However, the UE does not need to accurately know the analog beam groups(or the analog beams), and may measure in-symbol received power (e.g.,an xRSSI value or xRSRQ utilizing xRSSI) for time resources (which arepre-agreed or configured through a higher-layer signal) such that thesame analog beam group (or analog beam) is applied.

In the New RAT system to which the present invention is applicable, ifthe UE has a plurality of Rx antennas, the UE may apply an RX (receiver)beamforming technique to transmitted signals. At this time, the RX beamapplied by the UE may depend on which analog beam group (or analog beam)is applied, and the interference level experienced by the UE may alsodepend on the Rx beam. That is, the level of interference experienced bythe UE may depend on an analog beam group (or analog beam) applied bythe base station.

Accordingly, when the UE intends to measure xRSRQ for each specificanalog beam group (or analog beam), the UE may measure xRSRP and xRSSIfor each analog beam group (or analog beam). At this time, the UE maymeasure xRSSI corresponding to each analog beam group (or analog beam)only for a symbol in which the corresponding analog beam group (oranalog beam) is applied.

3.3.2. Second Method for Measuring and Reporting In-Symbol ReceivedPower

In measuring in-symbol received power (e.g., xRSSI) (for a specificTRP), the UE calculates an average RX beam based on signals applied (orknown) for K analog beam groups (or analog beams). Subsequently, the UEmay apply the RX beam to (any) reception symbols to measure in-symbolreceived power (e.g., xRSSI) for each of the analog beam groups (oranalog beams) and report RRM information (e.g., an xRSSI value or xRSRQutilizing xRSSI). That is, the UE may measure and report a total of KxRSSIs.

Here, as the average RX beam, an RX analog beam applied for reception atthe UE side may be applied.

In the case of the first method for measuring and reporting in-symbolreceived power described above, for a cell for which xRSRQ (or xRSSI) isto be measured, the UE needs to know which analog beam group (or analogbeam) is applied for each symbol in which the UE intends to measurexRSSI. However, in the New RAT system in which an analog beam group (oranalog beam) is changeable on a symbol-by-symbol basis, knowing whichanalog beam group (or analog beam) is applied for any symbol may requirean excessively high signaling overhead.

Accordingly, as an alternative method for measuring xRSSI according toapplication of a specific analog beam group (or analog beam), thepresent invention proposes that the UE calculate an average RX beam foreach analog beam group (or analog beam) based on signals (e.g., xPBCH,synchronization signal, BRS) already known about analog beam groups (oranalog beams) applied thereto, and apply the RX beam to (any) receptionsymbols to measure xRSSI for each analog beam group (or analog beam).

In addition, the UE according to the present invention may measure andreport the interference intensity after performing cancellation on theRRM RS in a resource in which the RRM RS is transmitted, or may measureand report the interference intensity in a muting resource for which aresource region and a numerology are predetermined.

3.4. Methods for Reporting RRM Measurement Results

3.4.1. First Method for Reporting RRM Measurement Results

The TRP may instruct reporting of aperiodic RRM measurement results(e.g., xRSRP or xRSRQ) (for a specific analog beam group or analog beam)over a dynamic control signal (e.g., dynamic control information (DCI),etc.), and the UE receiving the instruction may report the RRMmeasurement result to the base station over an L1 signal (e.g., a PHYlayer signal) or an L2 signal (e.g., a MAC layer signal) at a pre-agreedtime.

Here, the TRP may instruct the UE to report an aperiodic RRM RS receivedpower measurement value while indicating a UL resource to the UE throughthe DCI.

More specifically, in the conventional LTE system, the RRM measurementreporting is performed in a relatively semi-static manner in which theUE reports the measured value of the RRM measurement over a higher-layersignal. On the other hand, in the New RAT system to which the presentinvention is applicable, since the analog beam group (or analog beam)may be changed on a symbol-by-symbol basis, the UE may be required toquickly report the measured value of an RRM measurement result (e.g.,xRSRP or xRSRQ) for the analog beam group (or analog beam). Accordingly,when the UEs report RRM measurement result (e.g., xRSRP or xRSRQ)information about analog beam groups (or analog beams) in a short cycle,the base station may opportunistically apply an analog beam group (oranalog beam) proper at the moment based on the information.

As a method for this operation, the base station according to thepresent invention may instruct reporting of an aperiodic RRM measurementresult (e.g., xRSRP or xRSRQ) for a specific analog beam group (oranalog beam) through the DCI, and a UE receiving the instruction mayreport the RRM measurement result (e.g., xRSRP or xRSRQ) to the basestation using the L1 signal or the L2 signal after an agreed time fromthe moment of instruction.

3.4.2. Second Method for Reporting RRM Measurement Results

In the case where the UE measures and reports RRM measurement (e.g.,xRSRP, xRSRQ) for each antenna port of an RRM RS (for a specific TRP),the UE may report the RRM measurement result using one of the followingmethods:

(1) Report the RRM measurement result for each antenna port;

(2) Report the RRM measurement result for (specific) antenna port(s);

(3) Report an averaged RRM measurement result (for antenna ports);

(4) Report the RRM measurement results for each antenna port for Mselected (e.g., M best) beams;

(5) Report an averaged RRM measurement result for antenna portscorresponding to M selected (e.g., M best) beams.

Herein, the UE may report the measured RRM value including the TRP indexor analog beam index information for RRM measurement.

As a specific example, when the UE is capable of performing RRMmeasurement for each antenna port of the RRM RS for a specific TRP, theRRM measurement result report on an antenna port where the receivedpower (e.g., xRSRP) of the RRS RS is excessively low may not be usefulinformation from the TRP perspective. Therefore, the TRP may instructthe UE to report RRM measurement results for the M antenna ports withthe highest RRM RS received powers (or with the best RRM measurementvalue in terms of average SINR (signal to interference and noise powerratio)) or pre-agree with the UE about the reporting.

In a further embodiment, when the UE performs RRM measurement for eachcombination of an antenna port of the RRM RS and a symbol index as inthe second method for measuring and reporting RRM RS received powerdescribed above, the UE may report the RRM measurement result using oneof the following methods:

1) Report RRM measurement results for each combination of an antennaport and a symbol index;

2) Report an RRM measurement results for (specific) combination(s) of anantenna port and a symbol index;

3) Report an RRM measurement result for each averaged symbol index (forantenna ports within the same symbol);

4) Report an RRM measurement result for each averaged antenna port (forthe symbols of the same antenna port).

Here, in methods 1), 2) and 3), the UE may report only M RRM measurementresults having the highest RRM RS received powers (or best RRMmeasurement values in terms of average SINR).

3.4.3. Third Method for Reporting RRM Measurement Results

When the UE performs RRM measurement, the UE may determine an RRMmeasurement target (or a target of the report) using one of thefollowing methods:

(1) All TRPs (satisfying a certain event);

(2) Antenna ports of all RRM RSs (satisfying a certain event);

(3) Some TRPs (satisfying a certain event) (up to M TRPs per time unit);

(4) Some antenna ports (satisfying a certain event) (up to M antennaports per time unit).

Herein, when the UE reports the RRM measurement value, the UE may reportthe unique ID information about the measurement target (e.g., TRP ID,RRM RS sequence, antenna port number, etc.) as well.

In addition, when the UE performs RRM measurement for each RRM RSantenna port in the TRP, the target of the RRM measurement result reportmay be determined according to the first RRM measurement resultreporting method described above.

In the New RAT system applicable to the present invention, if each TRPmanages a plurality of analog beams and the UE performs RRM measurementfor each analog beam, the RRM measurement targets to be measured by theUE may greatly increase in number compared to the conventional LTEsystem and thus the complexity of the UE may increase. On the otherhand, as the RRM measurement results increase, the effectiveness of eachRRM measurement result may decrease. Therefore, the UE may be configuredto perform only an appropriate level of RRM measurement.

In this respect, when the UE according to the present invention performsRRM measurement (for the antenna ports of a specific TRP group or theRRM RS), the targets on which the RRM measurement is performed may belimited as described in (1) to (4) above.

3.4.4. Fourth Method for Reporting RRM Measurement Results

If the maximum number of measurable RRM measurement targets is definedas the RRM capability of the UE when the UE performs RRM measurement,the UE according to the present invention may report the RRM capabilityto the base station.

Here, the basic unit of RRM measurement targets may be a TRP, an RRM RSantenna port or an (analog) beam index. In one example, the RRMcapability may be defined as the number of TRPs, the number of RRM RSantenna ports or the number of (analog) beam indexes.

In addition, when the UE receives a list of RRM measurement targetsaccording to the measurement configuration from a specific TRP, the UEmay perform measurement on up to the maximum number of RRM measurementtargets having higher priorities in the list as supported by the RRMcapabilities of the UE.

As described in the third RRM measurement result reporting methoddescribed above, in the New RAT system applicable to the presentinvention, if each TRP manages a plurality of analog beams and the UEperforms RRM measurement for each analog beam, the RRM measurementtargets to be measured by the UE may greatly increase in number comparedto the conventional LTE system and thus the complexity of the UE mayincrease. In this case, the maximum number of supportable RRMmeasurement targets may be limited according to the implementation ofthe UE, and this limitation may be defined as a kind of the RRMcapability of the UE. The RRM capability may be at least reported to aTRP from which the UE receives a service and be utilized as referenceinformation when the TRP instructs RRM RS (Type 2)-based RRMmeasurement.

3.5. Additional Features Applicable to the Present Invention

In this section, features additionally applicable to the RRM measurementand reporting method described above will be described in detail.

In the following description, “QCL (quasi-collocated) between twodifferent RS resources” means that a delay spread, a Doppler spread, aDoppler shift, an average gain, an average delay, and arrival/departureangles of a channel which may be derived from one RS resource areapplicable to other RS resources as well.

For simplicity of explanation, the report on the reception end analogbeam information of the UE is referred to as a beam state information(BSI) report, and a signal through which the UE requests a UL datatransmission resource for the BSI report is referred to as a beam stateinformation scheduling request (BSI-SR), and the DL control informationthrough which the base station makes a request to the UE for BSI-SRtransmission is referred to as BSI-SR triggering downlink controlinformation (DCI) or a DL beam sweeping indicator. Here, the BSI reportmay include M (≥1) best beam groups in terms of UE reception, RRMmeasurement value (e.g., xRSRP, xRSRQ) (measured with the BRS to whichthe corresponding analog beam is applied) for each best beam.

In the following description, a specific analog beam used to provide adata service to a UE when a base station transmits a DL signal to the UEin the New RAT system to which the present invention is applicable isreferred to as a serving beam.

3.5.1. First Additionally Applicable Feature

When a base station configures an aperiodic RRM RS to be transmitted toa UE in a plurality of symbols, the base station may deliver, to the UE,a plurality of pieces of configuration information including thefollowing information about the RRM RS, using a higher-layer signal.

(1) Positions of symbols in which the aperiodic RRM RS is transmitted.Here, the positions of the symbols may be relative position informationwith respect to a specific symbol (first symbol) in an SF (or TTI) inwhich the aperiodic RRM RS transmission is triggered.

(2) Analog beam (or analog beam group) information for each aperiodicRRM RS transmission symbol. Herein, as the analog beam (or analog beamgroup) information, the base station may inform the UE of a resource ofa (separately configured) periodic (or periodic transmissionopportunity-given) RRM RS (or BRS) which has a QCL relationship and issubjected to the same analog beam (or analog beam group) as the analogbeam (or analog beam group) information.

At this time, the base station may inform the UE that an aperiodic RRMRS conforming to specific configuration information among the pluralityof pieces of configuration information is transmitted in a specific SF(or TTI), using a dynamic control signal (e.g., DCI).

In addition, the aperiodic RRM RS may be utilized only for a UE in anRRC CONNECTED state which is capable of receiving a higher-layer signal(or a UE that has succeeded in making an initial connection with thebase station).

More specifically, in the New RAT system to which the present inventionis applicable, evolution of technology for improving energy efficiencyof a network as well as a UE is considered. From this point of view, amethod to reduce signals transmitted by the base station in the networkin an Always On state as much as possible may be considered.

For example, the base station according to the present invention maytransmit the aperiodic RRM RS in an on-demand manner in whichtransmission is performed at a request only when necessary, rather thantransmitting the RRM RS at all times. At this time, if the base stationis operating hybrid beamforming (or analog beamforming), the aperiodicRRM RS may also be transmitted by applying multiple beams thereto.

In this regard, the present invention proposes a structure in which anaperiodic RRM RS is transmitted for a plurality of symbols in an SF (orTTI) as one form of the aperiodic RRM RS to which multiple beams areapplied, and an independent analog beam (or analog beam group) isapplied for each symbol. However, the aperiodic RRM RS may be a signaltransmitted to a specific UE group rather than a cell-common signal.Accordingly, the analog beams (or analog beam groups) applicable to theaperiodic RRM RS may be some of the analog beams (or analog beam groups)applied to the periodic (or periodic transmission opportunity-given) RRMRS. As one example, if the base station performs transmission of theperiodic (or periodic transmission opportunity-given) RRM RS for 14analog beams, it may perform transmission of the aperiodic RRM RS foronly 7 analog beams among the 14 analog beams.

3.5.2. Second Additionally Applicable Feature

A UE according to the present invention may make a request to the basestation for (aperiodic) RRM RS resource transmission for analog beammeasurement (or RRM measurement), using one of the following methods.

(1) Request (aperiodic) RRM RS resource transmission through aUE-specific UL resource (under a specific condition)

Requesting (aperiodic) RRM RS resource transmission along with its ownserving beam information and/or measurement information about theserving beam through a non-UE-specific UL resource (under a specificcondition)

Here, the specific condition refers to a condition for determining thatanalog beam measurement (or RRM measurement) of the UE is needed. As anexample of the specific condition, whether or not the link quality(e.g., xRSRP, xRSRQ) for the serving beam is below a certain level,whether or not a certain time has elapsed after configuration of theserving beam may be applied, or the like may be applied.

Considering an energy efficient system as the New RAT system to whichthe present invention is applicable, an operation may be considered inwhich the base station manages (or uses) as few periodic RRM RSresources as possible in terms of RRM measurement, and the UE requestsadditional (aperiodic) RRM RS transmission as necessary.

More specifically, the UE having received confirmation of the servingbeam(s) may measure the link quality such as xRSRP or xRSRQ for theserving beam(s). Then, if the link quality drops below a certain level,the UE may make a request to the base station for an (aperiodic) RRM RSresource for new analog beam measurement.

At this time, the UE requesting the (aperiodic) RRM RS resource mayinform the base station of the serving beam information configuredtherefor in order to determine the analog beams for which the basestation needs to perform (aperiodic) RRM RS transmission.

Alternatively, if the (aperiodic) RRM RS resource transmission requestis transmitted in a UE-specific manner, the base station may recognizethe serving beam(s) configured for the UE. For example, the UE maytransmit the aperiodic RRM RS resource request in the form of a ULreference signal (RS) supporting multiplexing between a plurality of UEsas a type of scheduling request (SR).

Alternatively, the UE may transmit the (aperiodic) RRM RS resourcetransmission request to the base station together with the serving beaminformation thereof in a manner of transmitting UL data.

Upon receiving the (aperiodic) RRM RS transmission request from the UEaccording to the various methods described above, the base station mayor may not perform additional (aperiodic) RRM RS transmission under thedetermination of the network based on the request information receivedfrom multiple UEs.

3.5.3. Third Additionally Applicable Feature

If the base station is to perform analog beam measurement (or RRMmeasurement) based on a UL RS transmitted by the UE, the UE according tothe present invention may transmit the UL RS (for measurement) asfollows.

(1) The UE transmits the UL RS (for measurement) through a UL resourceabout which the UE has pre-agreed (with the network) (under a specificcondition).

(2) When the base station instructs the UE to transmit the UL RS (formeasurement) (under a specific condition), the UE transmits the UL RS(for measurement) according to the instruction.

Here, the specific condition refers to a condition under which it isdetermined that analog beam measurement (or RRM measurement) by the UEis needed. As an example of the specific condition, whether or not thelink quality (e.g., xRSRP, xRSRQ) for the serving beam is below acertain level, whether or not a certain time has elapsed afterconfiguration of the serving beam may be applied, or the like may beapplied.

In addition, the base station may configure whether to perform analogbeam measurement (or RRM measurement) based on the UL RS (formeasurement) transmitted by the UE for the UE through the systeminformation or a higher-layer signal.

In the New RAT system to which the present invention is applicable, onecell is composed of a plurality of TRPs, and a plurality of analog beamsmay be managed by each TRP. In this case, when the UE moves within thecell, the serving beam is frequently changed, and analog beammeasurement for configuring a new serving beam may be frequentlyperformed. In this case, the analog beam measurement in which the UEmeasures and reports the DL RS transmitted by the base station mayproduce a large time delay from the perspective of the UE which moves athigh speed. Accordingly, the present invention proposes a scheme inwhich the UE transmits a UL RS (for measurement) and the networkmeasures the UL RS (for measurement) and configures a serving beam.

In this proposal, transmission of the UL RS (for measurement) may beperformed at a time when the UE determines that analog beamconfiguration is necessary. However, if the UE transmits the UL RS (formeasurement) at any point in time, this requires the base station toreserve a large amount of resources for reception of the UL signal. Inother words, this operation may not be desirable.

Therefore, transmission of the UL RS (for measurement) may be performedin a UL resource about which the UE has pre-agreed with the network ormay be performed at a time indicated by the base station. In the lattercase, the UE may first send a request for UL RS transmission (formeasurement) or an analog beam measurement (or analog beam measurementresource) request to the base station, and then the base station mayinstruct the UL RS transmission (for measurement) as needed.

Alternatively, the UE sends its serving beam measurement informationthrough the CSI or the like, and the base station may instruct UL RStransmission (for measurement) based on the information.

The analog beam measurement (or RRM measurement) based on the UL RS (formeasurement) transmitted by the UE as described above may be useful onlywhen the number of UEs is significantly smaller than the number ofnetwork nodes. In addition, the configuration described above may beestablished and used only when the base station needs it.

3.5.4. Fourth Additionally Applicable Feature

In the case where the base station according to the present inventionperforms analog beam measurement (or RRM measurement) based on the UL RStransmitted by the UE, the base station may configure the UL RS (formeasurement) as follows:

(1) Configure the UL RS so as to be transmitted in multiple symbols.Here, the UL RS resources (e.g., time and frequency resources,scrambling ID) for each symbol may be configured independently. Inaddition, analog beams (or analog beam groups) applied symbol by symbolmay be configured independently;

(2) Configure the UL RS so as to be repeated in a symbol. Here, the ULRS in the symbol may be generated in an Interleaved Frequency DivisionMultiple Access (IFDMA) form (or Comb form), and the same sequence maybe repeated in one symbol. In addition, the analog beam (or the analogbeam group) may be independently configured for each iteration interval(in the symbol);

(3) There may be one or more symbols in which the UL RS is transmittedin combination of (1) and (2), and the UL RS may be configured so as tohave a plurality of analog beams (or analog beam groups) (correspondingto the iteration intervals) in each symbol. In this case, the analogbeams (or the analog beam groups) may be independently configured on aniteration interval basis in the symbol.

As a specific example, in the case where the base station performsanalog beam measurement (or RRM measurement) on the basis of a UL signaltransmitted by the UE, the UE may transmit the UL RS signalomni-directionally if possible because this will allow network nodes invarious directions to receive the signal. However, if the UE transmitsthe UL RS (for measurement) using an omnidirectional antenna or the likewithout applying the analog beams, the coverage area may be shrunk, andthus the network nodes that may listen to the UL RS may be limited.

Accordingly, the present invention proposes a scheme in which a UEtransmit the UL RS (for measurement) by applying an analog beam theretoand performs the beam sweeping operation to transmit the UL RS invarious directions. In this case, the UL RS may be transmitted through aplurality of symbols while having a different analog beam (or analogbeam group) for each symbol, or may be repeated in a symbol while havingdifferent analog beams (or analog beam groups) for each iterationinterval. In the latter case, UL RS transmission may be performed in aplurality of analog directions while minimizing resource use.

In summary, the UE according to the present invention may perform RRMreporting as follows.

First, the UE receives a signal transmitted by applying one or moreanalog beams thereto on a symbol-by-symbol basis. Here, the signalincludes an RRM reference signal (RS).

Here, the RRM RS may include one or more of a synchronization signal(SS) or a demodulation reference signal in a physical broadcast channel.

In this case, for example, the RRM RS may be transmitted within afrequency resource region of a predetermined size in a subframe in whichthe synchronization signal (SS) is transmitted, and the same numerologyas applied to the SS may be applied to the RRM RS.

As another example, the RRM RS may be transmitted within a frequencyresource region of a predetermined size within a subframe after apredetermined number of subframes from a subframe in which thesynchronization signal (SS) is transmitted.

As another example, the RRM RS may be transmitted within a frequencyresource region of a predetermined size in a predetermined subframe, anda numerology configured by default may be applied to the RRM RS.

As another example, the RRM RS may be generated by inserting one or moresamples of zero between the samples of an RRM RS sequence, which isgenerated based on the numerology configured by default, according tothe numerology applied by the base station transmitting the RRM RS, andthe UE may receive the RRM RS based on the numerology configured bydefault.

Subsequently, the UE performs RRM measurement including at least one ofreceived power measurement of the RRM RS and received power measurementfor a received signal in a specific symbol based on the received signal,and report the measured RRM information to the base station.

Here, the UE may additionally receive measurement configurationinformation from the base station. In this case, the RRM RS may betransmitted in a frequency resource region of a predetermined sizeindicated by the measurement configuration information in a subframeindicated by the measurement configuration information, and a numerologyindicated by the measurement configuration information may be applied tothe RRM RS.

Alternatively, the RRM RS may be transmitted through one or more antennaports, and an independent analog beam may be applied to each of the oneor more antenna ports.

In this case, different frequency resources and sequences may beallocated to the RRM RSs for the one or more antenna ports.Alternatively, the UE may measure the received powers of the RRM RSs foreach antenna port in order to perform received power measurement of theRRM RS.

If the RRM RS is configured by a plurality of types, the UE mayindependently measure received power of each type of the RRM RS asreceived power measurement of the RRM RS, or may measure a single valueof RRM received power by applying a weight of a certain magnitude to thereceived power of each type of RRM RS as received power measurement ofthe RRM RS.

Alternatively, the UE may measure received power for a received signalwithin a specific symbol for each of the one or more analog beams asreceived power measurement for the received signal in the specificsymbol.

Alternatively, the UE may additionally receive instruction informationinstructing reporting of an aperiodic RRM measurement result from thebase station. Then, the UE may report the measured RRM information tothe base station through a physical layer signal or a medium accesscontrol (MAC) signal after a predetermined time from the moment at whichthe instruction information is received.

If the RRM RS is transmitted through one or more antenna ports, themeasured RRM information reported by the UE to the base station mayinclude one of RRM measurement result information averaged over the oneor more antenna ports, RRM measurement result information per antennaport for a certain number of analog beams of the one or more analogbeams, and RRM measurement result information averaged over the antennaports for a certain number of analog beams of the one or more analogbeams.

If the RRM RS is transmitted through one or more antenna ports, the UEmay perform RRM measurement on one or more antenna ports satisfying aspecific condition, and the measured RRM information may includeidentification information about the one or more antenna portssatisfying the specific condition.

Alternatively, the UE may additionally report to the base station amaximum number of RRM measurement targets that the UE can measure, andreceive measurement configuration information from the base station. Atthis time, the RRM RS may be transmitted in a frequency resource regionof a predetermined size indicated by the measurement configurationinformation in a subframe indicated by the measurement configurationinformation, and the UE may perform RRM measurement only on RRMmeasurement targets corresponding to the maximum number of RRMmeasurement targets among the RRM measurement targets indicated by anRRM measurement target list included in the measurement configurationinformation.

Here, the signal may be transmitted by applying one or more independentanalog beams to each symbol.

4. Device Configuration

FIG. 15 is a diagram illustrating configurations of a UE and a basestation capable of being implemented by the embodiments proposed in thepresent invention. The UE shown in FIG. 15 operates to implement theembodiments of the RRM reporting method described above.

A UE 1 may act as a transmission end on a UL and as a reception end on aDL. A base station (eNB) 100 may act as a reception end on a UL and as atransmission end on a DL.

That is, each of the UE and the base station may include a Transmitter(Tx) 10 or 110 and a Receiver (Rx) 20 or 120, for controllingtransmission and reception of information, data, and/or messages, and anantenna 30 or 130 for transmitting and receiving information, data,and/or messages.

Each of the UE and the base station may further include a processor 40or 140 for implementing the afore-described embodiments of the presentdisclosure and a memory 50 or 150 for temporarily or permanently storingoperations of the processor 40 or 140.

The UE 1 receives configured as above receives, from the base station100, a signal transmitted by applying one or more analog beams on asymbol-by-symbol basis through the receiver 20. Here, the signalincludes an RRM RS. The RRM RS may include a SS or a DM-RS in a PBCH.

Subsequently, the UE 1 performs RRM measurement including at least oneof received power measurement of the RRM RS and received powermeasurement for a received signal in a specific symbol based on thesignal (e.g., RRM RS) received from the base station. Then, the UE 1reports the measured RRM information to the base station 100 through thetransmitter 10.

The Tx and Rx of the UE and the base station may perform a packetmodulation/demodulation function for data transmission, a high-speedpacket channel coding function, OFDM packet scheduling, TDD packetscheduling, and/or channelization. Each of the UE and the base stationof FIG. 15 may further include a low-power Radio Frequency(RF)/Intermediate Frequency (IF) module.

Meanwhile, the UE may be any of a Personal Digital Assistant (PDA), acellular phone, a Personal Communication Service (PCS) phone, a GlobalSystem for Mobile (GSM) phone, a Wideband Code Division Multiple Access(WCDMA) phone, a Mobile Broadband System (MBS) phone, a hand-held PC, alaptop PC, a smart phone, a Multi Mode-Multi Band (MM-MB) terminal, etc.

The smart phone is a terminal taking the advantages of both a mobilephone and a PDA. It incorporates the functions of a PDA, that is,scheduling and data communications such as fax transmission andreception and Internet connection into a mobile phone. The MB-MMterminal refers to a terminal which has a multi-modem chip built thereinand which can operate in any of a mobile Internet system and othermobile communication systems (e.g. CDMA 2000, WCDMA, etc.).

Embodiments of the present disclosure may be achieved by various means,for example, hardware, firmware, software, or a combination thereof.

In a hardware configuration, the methods according to exemplaryembodiments of the present disclosure may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the methods according to theembodiments of the present disclosure may be implemented in the form ofa module, a procedure, a function, etc. performing the above-describedfunctions or operations. A software code may be stored in the memory 50or 150 and executed by the processor 40 or 140. The memory is located atthe interior or exterior of the processor and may transmit and receivedata to and from the processor via various known means.

Those skilled in the art will appreciate that the present disclosure maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent disclosure. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of thedisclosure should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein. It is obvious to those skilled in the art thatclaims that are not explicitly cited in each other in the appendedclaims may be presented in combination as an embodiment of the presentdisclosure or included as a new claim by a subsequent amendment afterthe application is filed.

The present disclosure is applicable to various wireless access systemsincluding a 3GPP system, and/or a 3GPP2 system. Besides these wirelessaccess systems, the embodiments of the present disclosure are applicableto all technical fields in which the wireless access systems find theirapplications. Moreover, the proposed method can also be applied tommWave communication using an ultra-high frequency band.

What is claimed is:
 1. A method of performing Radio Resource Management(RRM) reporting by a user equipment in a wireless communication system,the method comprising: performing RRM measurements; and reportinginformation on the RRM measurements, wherein the RRM measurements areperformed per beam, wherein a RRM measurement among the RRM measurementsis performed based on RSs for a same beam, and wherein the RSs comprise(i) a synchronization signal (SS) and (ii) a demodulation referencesignal for a physical broadcast channel.
 2. The method of claim 1,wherein the information comprises the RRM measurements measured byapplying a weight having a predetermined magnitude to a certain RRM RSamong the RSs.
 3. The method of claim 1, further comprising: receivinginstruction information instructing reporting of an aperiodic RRMmeasurement result; and reporting the information on the RRM measurementthrough a physical layer signal or a Medium Access Control (MAC) layersignal after a predetermined time from when the instruction informationis received.
 4. The method of claim 1, wherein the RRM measurementscomprises: each of reference signal received powers (RSRPs) per beam;and each of reference signal received qualitys (RSRQs) per beam.
 5. Themethod of claim 1, wherein the RRM measurements are measured only in oneor more symbols in which the RSs are transmitted by applyingcorresponding beam.
 6. A user equipment configured to perform RadioResource Management (RRM) reporting to a base station in a wirelesscommunication system, the user equipment comprising: a transmitter; areceiver; at least one processor; and at least one computer memoryoperably connectable to the at least one processor and storinginstructions that, when executed by the at least one processor, performoperations comprising: performing RRM measurements; and reporting theinformation on the RRM measurements, wherein the RRM measurements areperformed per beam, wherein a RRM measurement among the RRM measurementsis performed based on RSs for a same beam, and wherein the RSs comprise(i) a synchronization signal (SS) and (ii) a demodulation referencesignal for a physical broadcast channel.
 7. The user equipment of claim6, wherein the information comprises the RRM measurements measured byapplying a weight having a predetermined magnitude to a certain RRM RSamong the RSs.
 8. The user equipment of claim 6, wherein the operationsfurther comprise: receiving instruction information instructingreporting of an aperiodic RRM measurement result; and reporting theinformation on the RRM measurement through a physical layer signal or aMedium Access Control (MAC) layer signal after a predetermined time fromwhen the instruction information is received.
 9. The user equipment ofclaim 6, wherein the RRM measurements comprises: each of referencesignal received powers (RSRPs) per beam; and each of reference signalreceived qualitys (RSRQs) per beam.
 10. The user equipment of claim 6,wherein the RRM measurements are measured only in one or more symbols inwhich the RSs are transmitted by applying corresponding beam.